The purpose of this paper is to present information on operational experience, of renewable marine energy converters (MECs). In reality, there is relatively little operational experience with wave energy converters (WECs) and tidal stream devices (TSDs), and no published material, since in general only prototypes have been exposed to operational conditions at test or demonstration sites. However, there is good experience of wind devices, both on-shore and off-shore, so this will form the basis of the analysis, with a focus on its applicability to MECs. Where information is available for WECs and TSDs, we will elaborate and consider its significance.